Keyboard ghosting and rollover test

How to run the keyboard ghosting test

1. Press Start keyboard test, or click the keyboard drawing.
2. Press and hold keys one by one without letting go. Each key that registers lights up and Held now goes up.
3. Most keys at once keeps your record. When adding another key no longer raises Held now, you have hit your keyboard's limit for that combination.
4. Work through the Combos to try list: run + jump (W, A, Shift, Space), Q W E R, Ctrl + Shift + A + S, and the home row A S D F J K L. Each shows how many of its keys were held together, for example "3 / 4".
5. Hold Esc for one second or press Stop capturing keys when you are done; Reset starts over.

Under the record you get a plain verdict. More than 6 keys at once means N-key rollover or close to it. Exactly 6 is typical for 6-key rollover. Fewer than 6 means the keyboard limits some combinations, so try others: many keyboards block only certain groups of keys.

Ghosting, jamming and anti-ghosting explained

Most keyboards do not wire each key separately. The keys sit in a grid of rows and columns, and the controller scans the grid to see which crossings are closed. With three keys pressed at the corners of a rectangle, the fourth corner looks pressed too. Two things can happen:

• Ghosting: the keyboard reports that fourth key even though you never pressed it. On this page that shows as a key lighting up that you did not touch.
• Jamming (blocking): to avoid ghosts, the keyboard refuses the extra key. This is what most "anti-ghosting" keyboards do for the combos they can't resolve. Here the combo shows blocked?, because one of its keys never arrived while the others were held.

Keyboards with a diode on every switch, common on mechanical and gaming boards, avoid the problem completely: every key can be read independently.

If the page says a key was released that it never saw pressed, the keyboard dropped that press. That is another sign of a blocked combination.

6KRO vs NKRO: what the number means

Rollover is how many keys a keyboard can report at once. 6KRO (6-key rollover) comes from the USB "boot" report format: six normal keys plus the modifiers (Ctrl, Shift, Alt, Windows/⌘) on top. NKRO (N-key rollover) means any number of keys. Many gaming keyboards can do both and switch with a key combination or a setting in their software, because some older BIOS screens only understand the boot format.

For games, 6KRO is almost always enough: you rarely hold more than four or five keys. What matters more is that the combos you use are not blocked, which is exactly what the combo list checks. For fast typing, rollover helps when your fingers overlap keys.

Your operating system, a USB hub or the browser can add their own limit, so a low number here is not always the keyboard's fault. Some keyboards also give different results over Bluetooth and cable. Test both if you use both.

Laptop and wireless keyboards

Laptop and budget membrane keyboards usually have no anti-ghosting beyond a few protected keys (often W A S D and the arrows), so seeing 2 or 3 keys in some corners of the board is normal, not a defect. Compare with a friend's keyboard of the same model before deciding something is broken.

Related checks: the keyboard polling rate test estimates how often your keyboard reports, the spacebar clicker and typing test put the keys to work, and the laptop keyboard guide helps when keys fail completely. The results guide explains the numbers on all our tests. This test runs in your browser and nothing you press is recorded or uploaded. More tools: device tests.